Stanisław Ehrlich, Grupy nacisku w strukturze politycznej kapitalizmu [Pressure Groups in the Political Structure of Capitalism], Warszawa 1962, PWN. Contemporary Central & East European Law, [S. l.], n. 4, p. 40–41, 1965. Disponível em: https://czasopisma.inp.pan.pl/index.php/cceel/article/view/1700. Acesso em: 6 oct. 2025.